Rotary impact tool

ABSTRACT

A rotary impact tool having a fluid-operated motor having a rotor with a tubular extension to which a hammer is slidably mounted, an anvil normally spaced axially from the hammer, drive means including clutch means for rotating the anvil with rotation of the rotor and a cam means to cam the hammer axially into engagement with the anvil and with both the cam and clutch means being substantially wholly positioned within the recess of the tubular extension of the rotor.

United States Patent [72] Inventor Paul A. Biek Primary Examiner-Ernest R. Purser Houston, Tex. AttorneysRobert W. Mayer, Daniel Rubin, Raymond T. {2] Appl No. 834,278 Majesko, William E. Johnson. Jr, Roy L Van Winkle and [22] Filed June 18, 1969 Eddie E Scott [45] Patented June l, 1971 [73] Assignee Dresser Industries. Inc.

Houston, Tex.

[54] ROTARY IMPACT TOOL ll clalms4nrawlng Flgs' ABSTRACT: A rotary impact tool having a fluid-operated U-S- motor having a rotor a t b la extension t a [5 l] Int. Cl 325d /02 hammer is slidably mounted, an anvil normally spaced axially Field of Search from the hammer, drive means including clutch means for rotating the anvil with rotation of the rotor and a cam means Reerences cued to cam the hammer axially into engagement with the anvil and UNITED TA E AT with both the cam and clutch means being substantially wholly 3,156,334 1 1/1964 Hoza 173/93.6 positioned within the recess of the tubular extension of the re- 3,2l2,590 10/1965 Hoza et al l73/93.6 tor.

I I I I I I 63 t i x I J \J 66 72 Iv Y ROTARY IMPACT TOOL SUMMARY The present invention relates to an improved rotary impact tool.

An object of the present invention is to provide an improved rotary impact tool which has increased rigidity in its connections for imparting impact so that a minimum of energy stored in the rotating inertial mass is dissipated.

Another object of the present invention is to provide an improved impacttool having improved motor performance, improved output performance and a minimum overall length.

A further object is to provide an improved rotary impact tool having a rotor with adequate depth for blade movement in which the length of the tool is minimized.

Still another object is to provide an improved rotary impact tool having an improved efficiency.

A still further object is to provide an improved rotary impact tool which is free running even under axial loads.

BRIEF DESCRIPTION OF THE DRAWINGS These and other-objects and advantages of the present invention are hereinafter set forth and explained in detail in reference to the drawings wherein:

FIG. I is an elevation view of a rotary impact tool in which the improvements of the present invention have been included.

FIG. 2 is a longitudinal sectional view of the rotor, hammer and anvil of the improved tool of the present invention.

FIG. 3 is an exploded view of the drive connections from the rotor to the anvil.

FIG. 4 is an enlarged view of the bearing mounting of the rotor.

DESCRIPTION OF THE PREFERRED EMBODIMENT Rotary impact tools have in the past been used for a variety of applications such as tightening nuts. In order to have a wellbalanced tool it has been emphasized in the past that the length of the tool should be kept to a minimum.'Some condensations of the components of the tool have resulted in changing the output of the fluid-responsive rotor or the impact delivered by theoutput end ofthe tool. Since these tools all include a means for releasably connecting the rotor to the anvil and a cam for moving the hammer into impacting engagement with the anvil when the resistance to normal rotation of the anvil exceeds a certain preselected torque, the limitation of the length has resulted in a flexibility of connections to the hammer so that the full energy available for impact is not achieved because a portion of such energy is utilized in overcoming this flexibility. The improved rotary impact tool of the present invention provides an improved structure having a minimum length, an efficient driving means and a relatively rigid connection to the hammer so that the aforementioned flexibility losses are minimized.

The improved tool T of the present invention is illustrated in FIG. I as having a pistol grip secured to the housing 12 and atrigger 14 which controls the flow of fluid from a suitable source (not shown) into the connection 16 and to the rotor 18 (FIG. 2). A suitable exhaust vent (not shown) is provided to exhaust the fluid from the housing 12 after it has expanded against the rotor 18.

The rotor 18 is of the sliding vane type and is mounted for rotation between the front bearing plate 20 and the rear hearing plate 22 by suitable bearing means. The bearing means includes the ball bearing 24 and seal 26 positioned between the front end of the rotor 18 and the front bearing plate 20 and the ball bearing 28 and the roller thrust bearing 30 positioned between the rear end of the rotor 18 and the rear bearing plate 22. As best seen in FIG. 4, the ball bearing 28 is mounted on a portion of the rotor 18 which extends to the rear and the annular flange 32 of the plate 22. The snap ring 34 retains the ball bearing assembly on such extension and the thrust bearing 30 includes the rollers 36, the inner race 38 and the outer race 40. The retaining ring 42 engages in an annular groove within the flange 32 to hold the thrust bearing 30 in its desired position. The thickness of inner race 38 is used to determine the clearance between the rotor 18 and the inner face of the bearing plate 22. The washer 44 urges the ball bearing 28 against the snap ring 34 to prevent the rotor 18 from drifting axially to the left. Axial thrusts to the right are imposed on thrust bearing 30 and not on ball bearing 28. The thrust bearing 30 thus protects the ball bearing 28 from thrust loads so that the rotor is freely rotatable responsive to pressure fluid.

The rotor I8 has an annular extension 46 which is connected to the hammer 48 and also defines the recess 50. The hammer 48 is mounted for rotation with the rotor 18 by the splined connection 52 which allows the hammer 48 to move axially to the left as hereinafter described. The anvil 54 is mounted for rotation within the housing and extends outwardly from the front end of the housing with a configuration suitable for driving a working member such as a socket. Both the hammer 48 and the anvil 54 include jaws and such jaws are in spaced relationship to each other so that the hammer 48 and the anvil 54 are not directly connected in their normal position. The anvil 54 defines an axial recess 56 and a small offset bore 58 which is adapted to receive the pin 60.

A releasable driving means is provided between the rotor 18 and the anvil 54. Such driving means includes the shaft 62, the carrier 64 and the resilient clutch member 66. The forward end of shaft 62 defines a slot 68 so that when shaft 62 is positioned within the recess 56 the pin 60 engages in the slot 68 to provide a direct driving connection between the shaft 62 and the anvil 54. The other end of shaft 62 is connected to the carrier 64 by a splined connection as shown. The resilient clutch member 66 is provided with a taper on its rear surface to match the inner taper of the recess 50. Clutch member 66 also is hollow and mounted on an annular projection 70 of the carrier 64 and the forward end of clutch member 66 is provided with a taper matching the taper of the rear flange portion of carrier 64. Thus the clutch member when held tightly against the inner face of the recess 50 and the flange of carrier 64 provides a driving connection between the rotor 18 and the anvil 54. The spring 72 surrounds the shaft 62 and urges the washer 74 against the inner shoulder 76 on hammer 48 to the right and thereby urges hammer 48 away from engagement with anvil 54.

When the rotor 18 is rotating it will rotate the anvil 54 until the work being done by the anvil 54 offers sufflcient torque resistance to overcome the friction of the surface engagement of the clutch member 66 with the interior of the recess 50 and with the carrier 64. Whenever the rotor 18 continues to rotate because of the slippage of the clutch means, then the cam means of the present invention is actuated to cause the hammer 48 which always rotates with the rotor 18 to be cammed into impacting engagement with the anvil 54. The cam means includes the cam member 78 which is mounted on carrier 64 and includes a forward recess 80 and a rear cam surface 82. The pin 84 which is carried by the hammer 48 engages in the recess 80 and when the hammer 48 rotates while the anvil 54 is not rotating the pin 84 moves to a position to rotate the cam member 78 relative to the carrier 64. The roller 86 on the carrier rides on the cam surface 82 so that rotation of the cam member 78 moves the cam member 78 to the left or forward to move the hammer 48 into engagement with the anvil 54. After impact the spring 72 returns the hammer 48 out of engagement with the anvil 54 to ready it for another impacting engagement. The cam member 78 is released from engagement with the roller 86 when the anvil 54 is slightly rotated. With the hammer 48 returned, the rotor 18 and hammer 48 are free to accelerate for the next impact and the rotary impacting of the hammer 48 against the anvil 54 will continue in rapid succession until the supply of fluid to the rotor is discontinued.

By locating the clutch means and the cam means and a portion of the driving means within the recess 50 of the rotor extension 46, the length of the tool T has been minimized. The

splined connection 52 between the rotor 18 and the hammer 48 is of substantial length and at a large diameter to minimize the flexibility of the driving connection and thereby minimize the loss of energy when the hammer 48 impacts against the anvil S4.

The thrust on rotor 18 from the camming action acts toward the rear and is taken up by the thrust bearing assembly 30. The thickness of the thrust bearing assembly 30 is slightly greater than the dimension from the inner surface of the retainer ring 42 to the inner face of the bearing plate 22. This assures the proper rotor spacing from the bearing plate 22.

From the foregoing it can be seen that the improved impact tool of the present invention has a minimum of flexibility so that a maximum of the inertia of the rotating parts is delivered at impact. This is accomplished in a relatively short tool and the motor rotor has sufficient depth for the blades to provide improved tool performance.

What I claim is:

1. An impact tool, comprising:

a housing,

a rotor,

means for rotationally mounting said rotor within said housmeans for supplying a fluid into said housing to cause said rotor to rotate,

said rotor having an annular extension at one end thereof with a recess defined within said annular extension,

a hammer slidably mounted on said rotor extension for rotation with said rotor and slidable axially thereof,

an anvil rotationally mounted within said housing in a position axially spaced from said hammer whereby axial displacement of said hammer results in engagement of said anvil by said hammer, and

means releasably connecting said rotor to said anvil for driving said anvil,

said connecting means including a clutch means and a cam means positioned substantially wholly within said recess of said rotor extension,

said connecting means rotating said anvil with said rotor until said anvil resists turning and then said clutch means allows relative rotation between said hammer and said cam means so that said hammer is cammed axially by said cam means into engagement with said anvil to impart a rotary impact thereto.

2. An impact tool according to claim I wherein said connecting means includes a shaft carrier positioned within said recess,

a drive shaft being in driving engagement with said anvil at one end and extending through said hammer into engagement with said shaft carrier at its other end, and

said clutch means includes a clutch member positioned in said recess and engaging said carrier and the interior of said recess to form a releasable driving connection between said rotor and said carrier,

said cam means being adapted to engage said hammer to move it into engagement with said anvil when said rotor rotates independently of said anvil.

3. An impact tool according to claim 2 wherein said cam means includes a cam member having an axial bore therethrough, an indexing recess and a cam surface,

means for connecting said indexing recess to said hammer whereby rotation of said hammer with said anvil stationary rotates said cam member relative to said carrier, and

means coacting with said cam surface to move said hammer axially when said cam surface rotates relative to said carrier.

4. An impact tool according to claim 1 including means urging said hammer in a direction away from said anvil.

5. An impact tool according to claim I wherein said rotor mounting means includes ball bearing assemblies mounted at each end of said rotor for rotationally supporting said rotor within said housing, and

a thrust bearing assembly positioned between the housing and rotor to prevent movement of the rotor in the direction away from said hammer when said hammer is cammed into engagement with said anvil.

6. An impact tool according to claim 2 including a spring surrounding a portion of said shaft and engaging said hammer to urge said hammer in a direction away from said anvil.

7. A rotary impact tool comprising:

a housing,

a fluid-operated motor within said housing having a rotor,

means for conducting fluid to said motor to rotate said rotor,

a rotatable hammer having an axial recess, said rotor having a reduced end portion engaging within the recess in said hammer to connect said hammer and rotor for rotation together with said hammer being axially slidable on said reduced end portion of said rotor,

said rotor end portion defining a recess,

an anvil rotatably mounted in said housing, and driving means to rotate said anvil responsive to rotation of said rotor,

said driving means including clutch means for releasing the driving connection between said rotor and said anvil and cam means for moving said hammer into engagement with said anvil responsive to relative rotation of said rotor with respect to said anvil to thereby impart a rotary impact to said anvil,

said clutch means and said cam means being positioned sub stantially wholly within said rotor recess.

8. A rotary impact tool comprising a housing,

a motor including a rotor having a front end facing toward the front end of said housing and a rear end facing toward a rear end of said housing,

a hammer rotatably carried by and slidable on a front end portion of said rotor,

an anvil at the front end of said housing normally spaced axially from said hammer, and drive means for rotating said anvil responsive to rotation of said rotor,

said drive means terminating operatively connected to said motor at a location within the front end portion of said rotor and including cam means connected to move said hammer into engagement with said anvil to impart a rotary impact thereto.

9. A rotary impact tool according to claim 8 in which the front end of said rotor includes an annular extension having an internal recess in which said drive means terminates operatively connected to said motor.

10. A rotary impact tool according to claim 9 in which said annular rotor extension comprises the front end portion of said rotor on which said hammer is carried and slidable.

11. A rotary impact tool according to claim 10 including an axially extending splined interfit between said hammer and said annular rotor extension by which said hammer is carried and slidable on said extension. 

1. An impact tool, comprising: a housing, a rotor, means for rotationally mounting said rotor within said housing, means for supplying a fluid into said housing to cause said rotor to rotate, said rotor having an annular extension at one end thereof with a recess defined within said annular extension, a hammer slidably mounted on said rotor extension for rotation with said rotor and slidable axially thereof, an anvil rotationally mounted within said housing in a position axially spaced from said hammer whereby axial displacement of said hammer results in engagement of said anvil by said hammer, and means releasably connecting said rotor to said anvil for driving said anvil, said connecting means including a clutch means and a cam means positioned substantially wholly within said recess of said rotor extension, said connecting means rotating said anvil with said rotor until said anvil resists turning and then said clutch means allows relative rotation between said hammer and said cam means so that said hammer is cammed axially by said cam means into engagement with said anvil to impart a rotary impact thereto.
 2. An impact tool according to claim 1 wherein said connecting means includes a shaft carrier positioned within said recess, a drive shaft being in driving engagement with said anvil at one end and extending through said hammer into engagement with said shaft carrier at its other end, and said clutch means includes a clutch member positioned in said recess and engaging said carrier and the interior of said recess to form a releasable driving connection between said rotor and said carrier, said cam means being adapted to engage said hammer to move it into engagement with said anvil when said rotor rotates independently of said anvil.
 3. An impact tool according to claim 2 wherein said cam means includes a cam member having an Axial bore therethrough, an indexing recess and a cam surface, means for connecting said indexing recess to said hammer whereby rotation of said hammer with said anvil stationary rotates said cam member relative to said carrier, and means coacting with said cam surface to move said hammer axially when said cam surface rotates relative to said carrier.
 4. An impact tool according to claim 1 including means urging said hammer in a direction away from said anvil.
 5. An impact tool according to claim 1 wherein said rotor mounting means includes ball bearing assemblies mounted at each end of said rotor for rotationally supporting said rotor within said housing, and a thrust bearing assembly positioned between the housing and rotor to prevent movement of the rotor in the direction away from said hammer when said hammer is cammed into engagement with said anvil.
 6. An impact tool according to claim 2 including a spring surrounding a portion of said shaft and engaging said hammer to urge said hammer in a direction away from said anvil.
 7. A rotary impact tool comprising: a housing, a fluid-operated motor within said housing having a rotor, means for conducting fluid to said motor to rotate said rotor, a rotatable hammer having an axial recess, said rotor having a reduced end portion engaging within the recess in said hammer to connect said hammer and rotor for rotation together with said hammer being axially slidable on said reduced end portion of said rotor, said rotor end portion defining a recess, an anvil rotatably mounted in said housing, and driving means to rotate said anvil responsive to rotation of said rotor, said driving means including clutch means for releasing the driving connection between said rotor and said anvil and cam means for moving said hammer into engagement with said anvil responsive to relative rotation of said rotor with respect to said anvil to thereby impart a rotary impact to said anvil, said clutch means and said cam means being positioned substantially wholly within said rotor recess.
 8. A rotary impact tool comprising a housing, a motor including a rotor having a front end facing toward the front end of said housing and a rear end facing toward a rear end of said housing, a hammer rotatably carried by and slidable on a front end portion of said rotor, an anvil at the front end of said housing normally spaced axially from said hammer, and drive means for rotating said anvil responsive to rotation of said rotor, said drive means terminating operatively connected to said motor at a location within the front end portion of said rotor and including cam means connected to move said hammer into engagement with said anvil to impart a rotary impact thereto.
 9. A rotary impact tool according to claim 8 in which the front end of said rotor includes an annular extension having an internal recess in which said drive means terminates operatively connected to said motor.
 10. A rotary impact tool according to claim 9 in which said annular rotor extension comprises the front end portion of said rotor on which said hammer is carried and slidable.
 11. A rotary impact tool according to claim 10 including an axially extending splined interfit between said hammer and said annular rotor extension by which said hammer is carried and slidable on said extension. 